cp's OEIS Frontend

A086540 Numbers n such that n and n+1 both are members of A074997; i.e., on the one hand n-1 and n+1 have the same prime signature, on the other hand n and n+2 have the same prime signature.

%I A086540 #11 Jul 29 2017 13:19:19
%S A086540 18,55,248,340,348,722,850,949,1061,1148,1204,1205,1241,1277,1314,
%T A086540 1315,1667,1672,2148,2716,2948,2949,3258,3581,3650,3651,4044,4265,
%U A086540 4627,4842,5092,5093,5451,5741,5765,6244,6355,6356,6565,6640,6851,6963,7362,7404
%N A086540 Numbers n such that n and n+1 both are members of A074997; i.e., on the one hand n-1 and n+1 have the same prime signature, on the other hand n and n+2 have the same prime signature.
%H A086540 Charles R Greathouse IV, <a href="/A086540/b086540.txt">Table of n, a(n) for n = 1..10000</a>
%o A086540 (PARI) isok1(n) = vecsort(factor(n-1)[,2]) == vecsort(factor(n+1)[,2]);
%o A086540 isok(n) = isok1(n) && isok1(n+1); \\ _Michel Marcus_, Jul 28 2015
%Y A086540 Cf. A074997.
%K A086540 nonn
%O A086540 1,1
%A A086540 _Amarnath Murthy_, Aug 22 2003
%E A086540 More terms from _David Wasserman_, Mar 21 2005